What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[gooffeyguy]

Doing a block check test can help narrow it down too. It detects combustion products in the coolant.

https://www.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF

Good idea!

Lol

 

[mikez71]

Doing a block check test can help narrow it down too. It detects combustion products in the coolant.

Yeah, but at this point with coolant in the exhaust, what else could it be but head/headgasket? (crack in cylinder?)

but either way the tester won't tell me where, I figure head must come off..

 

[Doubeleive]

Yeah, but at this point with coolant in the exhaust, what else could it be but head/headgasket? (crack in cylinder?)

but either way the tester won't tell me where, I figure head must come off..

for a $20 bet I would use the tester to see what it shows or does not show, you already thought it was the heater core....
I bet it is something under the hood be it head or not when you start it up whatever smell is under the hood gets pushed out the hood right into the nostrils
my hardest one was a literal pin hole leak in a radiator hose it only leaked when you shut the vehicle off for a second and that was it, little piss out and done not even enough to leave a drop on the ground. I think I only found it by accident.

 

[Sparksalot]

Yeah, but at this point with coolant in the exhaust, what else could it be but head/headgasket? (crack in cylinder?)

but either way the tester won't tell me where, I figure head must come off..

But it would tell you definitively if there is a leak into the coolant. Better to eliminate the easy stuff before tearing the engine open.

 

[mikez71]

for a $20 bet I would use the tester to see what it shows or does not show, you already thought it was the heater core....
I bet it is something under the hood be it head or not when you start it up whatever smell is under the hood gets pushed out the hood right into the nostrils

Very true! I hope you're right! (With my luck it will be head and heater core..)

Waiting for the expansion tank and a couple hoses first so I can try pressurizing again.
I would think with a pinhole that I could still pressurize it somewhat. (Or a small HG leak for that matter)

If no change, I will do the combustion gas check.. certainly don't want to pull the head for no reason.

 

[j91z28d1]

I've never had one that wouldn't build even a little pressure. even ones that spray coolent out of a hose. something isn't correct. not sure what, but it's a pretty large leak and above the water line. so that pretty much means how pump attachment itself.

 

[mikez71]

I've never had one that wouldn't build even a little pressure. even ones that spray coolent out of a hose. something isn't correct. not sure what, but it's a pretty large leak and above the water line. so that pretty much means how pump attachment itself.

Havent done it before, but totally agree!

I'm hoping its the tank seam and will try another tester shortly.

 

[j91z28d1]

Havent done it before, but totally agree!

I'm hoping its the tank seam and will try another tester shortly.

I don't mean to it to sound dumb but did you block off the over flow hose?

 

[mikez71]

I don't mean to it to sound dumb but did you block off the over flow hose?

View attachment 402694

I do have a smaller hose from radiator that connects to the tank above coolant level. Did order a new hose as well. Shouldn't have to plug it as it goes to the radiator I hope? I was going to disconnect it but couldnt find the right size plug and gave up.

 

[Doubeleive]

I don't mean to it to sound dumb but did you block off the over flow hose?

View attachment 402694

pretty sure the pressure tester fitting covers the overflow hole, it did on the wife 04 and there is little difference on the gmt800's